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10 May 2007 Do Fruit Flies Have Free Will?
under embargo until
16 May 2007 01:00 GMT
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Scientists Measure Spontaneity in Drosophila.
Free
will and true spontaneity exist … in fruit flies. This is what
scientists report in a groundbreaking study in the May 16, 2007 issue
of the open-access journal PLoS ONE.
“Animals and especially
insects are usually seen as complex robots which only respond to
external stimuli,” says senior author Björn Brembs from the Free
University Berlin. They are assumed to be input-output devices. “When
scientists observe animals responding differently even to the same
external stimuli, they attribute this variability to random errors in a
complex brain.” Using a combination of automated behavior recording and
sophisticated mathematical analyses, the international team of
researchers showed for the first time that such variability cannot be
due to simple random events but is generated spontaneously and
non-randomly by the brain. These results caught computer scientist and
lead author Alexander Maye from the University of Hamburg by surprise:
“I would have never guessed that simple flies who otherwise keep
bouncing off the same window have the capacity for nonrandom
spontaneity if given the chance.”
The researchers tethered
fruit flies (Drosophila melanogaster) in completely uniform white
surroundings and recorded their turning behavior. In this setup, the
flies do not receive any visual cues from the environment and since
they are fixed in space, their turning attempts have no effect. Thus
lacking any input, their behavior should resemble random noise, similar
to a radio tuned between stations. However, the analysis showed that
the temporal structure of fly behavior is very different from random
noise. The researchers then tested a plethora of increasingly complex
random computer models, all of which failed to adequately model fly
behavior.
Only after the team analyzed the fly behavior with
methods developed by co-authors George Sugihara and Chih-hao Hsieh from
the Scripps Institution of Oceanography at UC San Diego did they
realize the origin of the fly’s peculiar spontaneity. “We found that
there must be an evolved function in the fly brain which leads to
spontaneous variations in fly behavior” Sugihara said. “The results of
our analysis indicate a mechanism which might be common to many other
animals and could form the biological foundation for what we experience
as free will”.
Our subjective notion of “Free Will” is an
oxymoron: the term ‘will’ would not apply if our actions were
completely random and it would not be ‘free’ if they were entirely
determined. So if there is free will, it must be somewhere between
chance and necessity - which is exactly where fly behavior comes to
lie. “The question of whether or not we have free will appears to be
posed the wrong way,” says Brembs. “Instead, if we ask ‘how close to
free will are we?’ one finds that this is precisely where humans and
animals differ”.
The next step will be to use genetics to
localize and understand the brain circuits responsible for the
spontaneous behavior. This step could lead directly to the development
of robots with the capacity for spontaneous nonrandom behavior and may
help combating disorders leading to compromised spontaneous behavioral
variability in humans such as depression, schizophrenia or obsessive
compulsive disorder.
The research will appear in the May 16, 2007 issue of the open-access journal PLoS ONE.
[A
multimedia version of this story, with video and illustrations, is
available on Björn Brembs’ website, at http://brembs.net/spontaneous] |
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